See each measurement
Review the horizontal run, rise, roof angle, rafter length and overhang with a labelled diagram.
Jiffyjoker calculators
A practical tool for roof layout
Roof & Rafter Calculator
Estimate common-rafter length, roof pitch, rise, run, angle and horizontal overhang. Review the measurements, formula and labelled roof diagram together.
Google Play release is in review; launch availability is pending
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The listing may not open until Google completes its review and the app is available in your region.
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Clear geometry, in the units you use
Enter a building span and describe the roof using pitch, angle or rise. Switch between metric and imperial measurements, including fractional inches, and see how the result is derived. Core calculations work offline in the app.
Keep projects together
The optional one-time Pro unlock adds saved projects, named measurement sets, presets and configuration comparisons.
Take the details with you
Pro adds PDF reports, cut lists and material estimates with an explicit waste allowance.
Use as a geometry estimate only. The calculator does not size structural members or verify loads, materials, connections, local building codes or structural safety. Confirm measurements and construction decisions with applicable codes and a qualified professional.
How the common-rafter estimate works
For a simple roof section, the app treats the horizontal run and vertical rise as the two sides of a right triangle. The sloped length is estimated with √(run² + rise²). Pitch or angle can be used to derive the rise from the run.
The entered eave overhang is a horizontal projection beyond the bearing point. The app extends the same roof slope to estimate the rafter length to the fascia tail. It does not deduct ridge-board thickness or model compound cuts.
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